Monocrystalline SiC Layer Transfer on Low-Temperature Crystallized Carrier
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Solution Overview
Problem
The challenge lies in manufacturing high-quality composite structures with a thin layer of monocrystalline silicon carbide (c-SiC) on a lower-cost silicon carbide (SiC) support substrate, where achieving direct bonding of high quality between c-SiC and poly-crystalline SiC substrates is difficult due to surface roughness and the formation of amorphous layers, which affects vertical electrical conduction and introduces defects, increasing costs and complexity.
Innovation Solution
A method involving ion implantation to form a buried fragile plane in a donor substrate, followed by successive chemical vapor deposition and crystallization of support layers at controlled temperatures, with mechanical and chemical treatments to achieve a composite structure with a thin c-SiC layer on a poly-crystalline SiC support substrate, ensuring low defect density and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct bonding is used to join c-SiC thin film to p-SiC support substrate, then manufacturing cost is reduced and process is simplified, but bonding quality deteriorates due to surface roughness and amorphous layer formation
Solution Approach 1:
The patent applies preliminary surface treatment through ion implantation and plasma activation before bonding to modify surface properties. This pre-treatment creates a controlled amorphous layer and activates surface bonds, enabling subsequent direct bonding to achieve high-quality interfaces without requiring complex intermediate layers or post-bonding repairs.
Solution Approach 2:
The patent changes surface parameters through controlled ion implantation (energy, dose, species) and plasma treatment conditions to optimize surface reactivity and bonding characteristics. By adjusting these parameters, the process achieves optimal bonding quality while maintaining cost-effectiveness through direct bonding rather than requiring additional intermediate layers.
2Strength
If surface activation bonding with argon bombardment is used to promote covalent bond formation, then bonding energy increases, but amorphous layer formation deteriorates electrical conduction
Solution Approach 1:
The patent uses a carefully controlled amorphous layer as an intermediary between the c-SiC thin film and p-SiC substrate. This intermediary layer, formed through controlled ion implantation and plasma treatment, actually improves bonding quality by facilitating covalent bond formation while maintaining electrical conductivity through subsequent thermal annealing that crystallizes the interface region.
Solution Approach 2:
The patent exploits phase transitions by controlling the formation and subsequent crystallization of the amorphous SiO2 layer at the bonding interface. The layer transitions from amorphous (formed during surface treatment) to crystalline (after thermal annealing), thereby restoring electrical conductivity while maintaining the bonding strength gained during the amorphous phase.
3Manufacturing precision
If high temperature deposition is used for p-SiC production, then material quality improves, but cavity growth in brittle plane accelerates causing blistering
Solution Approach 1:
The patent applies preliminary low-temperature deposition to form an initial p-SiC layer before high-temperature processing. This preliminary layer acts as a buffer that prevents cavity coalescence and blistering during subsequent high-temperature deposition, allowing the process to achieve high material quality without structural failure.
Solution Approach 2:
The patent changes deposition temperature parameters through a multi-stage process: initial low-temperature deposition to form a defect-free foundation layer, followed by controlled high-temperature deposition for quality improvement. This parameter variation enables achieving high material quality while preventing cavity growth-induced blistering.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively produces a high-quality composite structure with improved electrical conductivity and reduced defect density, enabling the development of reliable power devices with enhanced performance and reduced manufacturing complexity and cost.
Implementation Method 1
a step of ion implantation of light species in the donor substrate, to form a buried brittle plane delimiting the thin layer
Implementation Method 2
a chemical vapor deposition assisted by direct liquid injection, at a temperature below 900°C, to form a support layer, said support layer being formed by a SiC matrix at least partially amorphous
Implementation Method 3
a heat treatment for crystallization of the support layer, at a temperature less than or equal to 1000°C, to form a crystallized support layer
Implementation Method 4
a separation step along the buried brittle plane, to form on the one hand a composite structure comprising the thin layer on the support substrate, and on the other hand the remainder of the donor substrate
Data Source
Figure 1~2b
Figure 2c(i)~2c(iii)
Figure 2c(iv)~2c(vi)
AI summary
The invention relates to a method for manufacturing a composite structure comprising a thin layer made of monocrystalline silicon carbide arranged on a carrier substrate made of silicon carbide, the method comprising: a) a step of providing a donor substrate made of monocrystalline silicon carbide, b) a step of ion implantation of light species into the donor substrate, to form a buried brittle plane delimiting the thin layer between said buried brittle plane and a free surface of said donor substrate, c) a succession of n steps of forming crystalline carrier layers, with n greater than or equal to 2; the n crystalline carrier layers being positioned on the front face of the donor substrate successively one on the other, and forming the carrier substrate; each formation step comprising: - direct liquid injection chemical vapour deposition, at a temperature below 900°C, to form a carrier layer, said carrier layer being formed by an at least partially amorphous SiC matrix, and having a thickness of less than or equal to 200 microns; - a crystallization heat treatment of the carrier layer, at a temperature of less than or equal to 1000°C, to form a crystalline carrier layer; d) a step of separation along the buried brittle plane, to form, on the one hand, a composite structure comprising the thin layer on the carrier substrate and, on the other hand, the rest of the donor substrate.